Hertzsprung-Russell diagram of the stars in M17 with PMS evolutionary tracks from MIST (solid black lines; Dotter 2016; Choi et al. 2016; Paxton et al. 2011, 2013, 2015). The blue dots represent the PMS stars with IR excess and emission lines in their X-shooter spectrum. The orange triangles represent the PMS stars without emission lines in the X-shooter spectrum, but with IR excess λ > 2.3 µm (Chini et al. 2005). The gray striped line is the birth line, and the straight black line to the left of the figure is the ZAMS. The dotted gray lines show the isochrones. The ages are indicated in a similar color in the figure.